Blast-furnace smelting



Patented Sept. 9, 1924.

* UNITED STATES PATENT OFFICE.

.THoMAs WILLARD cAvEns, or NICKELTON,

BLAST-FURNACE SMELTING.

No Drawing.

To all whom it may concern:

Be it known that I, THOMAS l VILLARD CAVERS, a citizen of Dominion of Canada, residing at Nickelton, Ontario, Canada, have invented certain new and useful Improvements in Blast-Furnace Smelting, of which the following is a specification.

The present invention relates to smelting non-ferrous metal ores, as well as :concenblown in at a level slightly above the normal slag level in the furnace, and combustion of the fuel maintains a slag-forming temperature at a point somewhat above the twyers, ordinarily referred to as thefocus of the furnace. At this zone ferrous with lime and other basic oxids present unite with silica and sometimes other acidulous OXlClS present in the charge, to produce a slag,

while the liberated remaining metal sulfide- (or metal in case of lead smelting) forms a liquid matte, both the matte (and the metal, if any) and the slag flowing downwardly from the focus into the crucible of the furnace, and the matte and slag are subsequently separated from each other by gravity separation while hot, the matte always being of much higher specific gravity than the slag.

The feature of the present invention, upon which novelty is predicated, is the introduction of steam into the furnace at a level below the slag-forming zone. The steam may be, and preferably. is, superheated before being introduced, and this steam is preferably introduced at about the level of the smelting twyers, or may be introduced at a somewhat lower level if desired. Itwould be possible to introduce the steam a short distance above the smelting twyers,

but I believe that the results would not be so favorable. In any event, the steam raising the iron content on'rnnio; CANADA.

Application filed January 25, 1921. Serial No. 4395870.

should be introduced below the slag-forming nucleus or focus of the furnace.

The steam so introduced abstracts a portion of the superheat from the streamlets of slag and matte flowing downwardly in the furnace. The term used, is intended to mean the amount ofheat carried by the matte and slag in: excess of that quantity. of heat I maintain the slag and matte in a freely molten condition. The steam, or the products of dissociation of the steam rise with the smelting air and react with metal sulfides, such as iron sulfide, ordinarily producing thereby some desulfurization of the matte or of metal sulfides about to melt. Any hydrogen sulfide produced by this reaction quickly burns in the air present and the steam so formed may react further with iron sulfide or other metal sulfides in the hot portions of the furnacesabove the slag-forming zone. The final gaseous and Vaporous reaction products, of course, pass upwardly through the charge in the furnace and out at its top.

I have found, by experimentation, that when steam is introduced in the manner above specified at about the level of the which :is necessary to the content of iron sulfide in the matte can begreatly reduced.

While I have above given a statement of my theoryas to the manner in which the steam operates, I do not desire to be bound by any specific theory of operation, in fact the steam may reactions which produce the slag and matte. On account of the high temperature in the furnace, course, impossible to state accurately just what reactions are going on there. EX- periments have further shown that the slagforming zone is lowered somewhat, that is to say, is drawn nearer to the twyer'level which is always desirable in blast furnace operation.

simply act as acatalyzer to assist in the chemical it is, of

It might be argued that the steam entering the furnace in a vaporized condition and leaving the furnace in a vaporized condi-I tion could not furnish heat in the furnace. The experiments have, however, shown that the results of raising the grade of the matte, of theslag and lowering the fusion zone or focus of the furnace, actually have been produced when steam was introduced at about the twyer level.

On account of, the fact that the introduction of steam is able to lower the slag-forming zone in the furnace, it will be obvious that somewhat less fuel will be necessary to operate the furnace than is used in ordinary smelting practice. This is true Whether the fuel is introduced at the top of the furnace or at the twyers.

On account of the higher grade of the matte and the higher iron content of the slag, increased capacity of the furnace necessarily results, whereby a given furnace is able to accommodate a greater quantity of charge per twenty-four hours.

I claim:

1. In the smelting of non-ferrous-metalcontaining materials, the improvement which comprises introducing steam into the blast furnace, at a level not substantially above the smelting twyers, While introducing sufficient air through the smelting twyers for burning any hydrogen sulfid formed thereby.

2. In the smelting of copper, and nickel ores and concentrates, the improvement which comprises introducing steam into the blast furnace at about the level where the air for the smelting operation is introduced, the amount of such air being sufliciently in excess of the amount necessary to burn the fuel, to also burn any hydrogen sulfid formed by such steam.

In testimony whereof I afix my signature.

THOMAS WILLARD CAVERS. 

